Electrode protection using a composite comprising an electrolyte-inhibiting ion conductor

ABSTRACT

Composite structures including an ion-conducting material and a polymeric material (e.g., a separator) to protect electrodes are generally described. The ion-conducting material may be in the form of a layer that is bonded to a polymeric separator. The ion-conducting material may comprise a lithium oxysulfide having a lithium-ion conductivity of at least at least 10−6 S/cm.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.15/459,152, filed Mar. 15, 2017, which is a continuation of U.S.application Ser. No. 14/624,641 (now U.S. Pat. No. 9,653,750), filedFeb. 18, 2015, which claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Application Ser. No. 61/941,734, filed Feb. 19, 2014, andU.S. Provisional Application Ser. No. 61/941,546, filed Feb. 19, 2014,which are incorporated herein by reference in their entirety for allpurposes.

TECHNICAL FIELD

Composite structures that include an ion-conducting material and apolymeric material (e.g., a separator) to protect electrodes aregenerally described.

BACKGROUND

Rechargeable and primary electrochemical cells oftentimes include one ormore protective layers to protect the electroactive surface. Dependingupon the specific protective layer(s), the protective layer(s) isolatesthe underlying electroactive surface from interactions with theelectrolyte and/or other components within the electrochemical cell. Inorder to provide appropriate protection of the underlying electrode, itis desirable that the protective layer(s) continuously cover theunderlying electrode and exhibit a minimal number of defects. Althoughtechniques for forming protective layer(s) exist, methods that wouldallow formation of protective layer(s) that would improve theperformance of an electrochemical cell would be beneficial.

SUMMARY

Composite structures that include an ion-conducting material and apolymeric material (e.g., a separator) to protect electrodes aregenerally described. Associated systems and methods are generallydescribed. The ion-conducting material can inhibit interaction betweenthe protected electrode and an electrolyte.

In one set of embodiments, electrochemical cells are described. Anelectrochemical cell may include, for example, a first electrodecomprising lithium as an electroactive material, a second electrode, anda composite positioned between the first and second electrodes. Thecomposite comprises a separator comprising pores having an average poresize, wherein the separator has a bulk electronic resistivity of atleast about 10⁴ Ohm-meters, and an ion conductor layer bonded to theseparator. The ion conductor layer has a lithium-ion conductivity of atleast at least 10⁻⁶ S/cm. The ion conductor layer comprises a lithiumoxysulfide having an oxide content between 0.1-20 wt % and/or whereinthe ion conductor layer comprises a lithium oxysulfide having an atomicratio of oxygen atoms to sulfur atoms (O:S) in the range of from 0.001:1to 1.5:1.

In one set of embodiments, electrochemical cells are described. Anelectrochemical cell may include, for example, a first electrodecomprising lithium as an electroactive material, a second electrode, anda composite positioned between the first and second electrodes. Thecomposite comprises a separator comprising pores having an average poresize, wherein the separator has a bulk electronic resistivity of atleast about 10⁴ Ohm-meters, and an ion conductor layer bonded to theseparator. The ion conductor layer has a lithium-ion conductivity of atleast at least 10⁻⁶ S/cm. The ion conductor layer comprises a lithiumoxysulfide having an oxide content between 0.1-20 wt % and/or whereinthe ion conductor layer comprises a lithium oxysulfide having an atomicratio of sulfur atoms to oxygen atoms (S:O) in the range of from 0.5:1to 1000:1.

An electrochemical cell may include, for example, a first electrodecomprising lithium as an electroactive material, a second electrode, anda composite positioned between the first and second electrodes. Thecomposite comprises a separator comprising pores having an average poresize, wherein the separator has a bulk electronic resistivity of atleast about 10⁴ Ohm-meters, and an ion conductor layer bonded to theseparator. The ion conductor layer has a lithium-ion conductivity of atleast at least 10⁻⁶ S/cm. The ion conductor layer comprises an atomicratio of sulfur:oxygen of between 1:1 to 100:1.

An electrochemical cell may include, for example, a first electrodecomprising lithium as an electroactive material, a second electrode, anda composite positioned between the first and second electrodes. Thecomposite comprises a separator comprising pores having an average poresize, wherein the separator has a bulk electronic resistivity of atleast about 10⁴ Ohm-meters, and an ion conductor layer bonded to theseparator. The ion conductor layer has a lithium-ion conductivity of atleast at least 10⁻⁶ S/cm. The ion conductor layer comprises a lithiumoxysulfide having an atomic ratio of oxygen atoms to sulfur atoms (O:S)in the range of from 0.001:1 to 1.5:1, e.g., in the range of from 0.01:1to 0.25:1.

An electrochemical cell (preferably an electrochemical cell as describedabove), wherein the electrochemical cell is a lithium-sulfur cell, maycomprise, for example, a first electrode comprising lithium, a secondelectrode comprising sulfur, a separator arranged between said firstelectrode and said second electrode, and a solid ion conductorcontacting and/or bonded to the separator, wherein said solid ionconductor comprises a lithium-ion conducting oxysulfide.

In some embodiments involving the electrochemical cells described aboveand herein, the ion conductor layer comprising the lithium oxysulfide isa part of a multi-layered structure comprising more than one ionconductor layers. In some instances, at least two layers of themulti-layered structure are formed of different materials. In otherinstances, at least two layers of the multi-layered structure are formedof the same material. The ion conductor layer comprising the lithiumoxysulfide may be in direct contact with each of the first electrode andthe separator.

In some embodiments involving the electrochemical cells described aboveand herein, the separator has a thickness between 5 microns and 40microns. The separator may have a bulk electronic resistivity of atleast 10¹⁰ Ohm meters, e.g., between 10¹⁰ Ohm meters and 10¹⁵ Ohmmeters.

In some embodiments involving the electrochemical cells described aboveand herein, the separator is a solid, polymeric separator. In somecases, the separator is a solid comprising a mixture of a polymericbinder and filler comprising a ceramic or a glassy/ceramic material. Incertain embodiments, the separator comprises one or more ofpoly(n-pentene-2), polypropylene, polytetrafluoroethylene, a polyamide(e.g., polyamide (Nylon), poly(ε-caprolactam) (Nylon 6),poly(hexamethylene adipamide) (Nylon 66)), a polyimide (e.g.,polynitrile, and poly(pyromellitimide-1,4-diphenyl ether) (Kapton®)(NOMEX®) (KEVLAR®)), polyether ether ketone (PEEK), and combinationsthereof.

In some embodiments involving the electrochemical cells described aboveand herein, the composite is formed by subjecting a surface of theseparator to a plasma prior to depositing the ion conductor layer on thesurface of the separator.

In some embodiments involving the electrochemical cells described aboveand herein, the lithium oxysulfide has a formula of x(yLi₂S+zLi₂O)+MS₂(where M is Si, Ge, or Sn), where y+z=1, and where x may range from0.5-3.

In some embodiments involving the electrochemical cells described aboveand herein, the ion conductor layer comprises a glass forming additiveranging from 0 wt % to 30 wt % of the inorganic ion conductor material.

In some embodiments involving the electrochemical cells described aboveand herein, the ion conductor layer comprises one or more lithium salts.A lithium salt may include, for example, LiI, LiBr, LiCl, Li₂CO₃, and/orLi₂SO₄. The one or more lithium salts is added to the inorganic ionconductor material at a range of, e.g., 0 to 50 mol %. In someembodiments involving the electrochemical cells described above andherein, the separator has an average pore size of less than or equal to5 microns, less than or equal to 1 micron, less than or equal to 0.5microns, between 0.05-5 microns, or between 0.1-0.3 microns.

In some embodiments involving the electrochemical cells described aboveand herein, the ion conductor layer has a thickness of less than orequal to 2 microns, less than or equal to 1.5 microns, less than orequal to 1 micron, less than or equal to 800 nm, less than or equal to600 nm, or between 400 nm and 600 nm.

In some embodiments involving the electrochemical cells described aboveand herein, the composite has a lithium ion conductivity of at least10⁻⁵ S/cm, at least 10⁻⁴ S/cm, or at least 10⁻³ S/cm at 25 degreesCelsius.

In some embodiments involving the electrochemical cells described aboveand herein, a ratio of a thickness of the ion conductor layer to theaverage pore size of the separator is at least 1.1:1, at least 2:1, atleast 3:1 or at least 5:1.

In some embodiments involving the electrochemical cells described aboveand herein, a strength of adhesion between the separator and the ionconductor layer is at least 350 N/m or at least 500 N/m. In someinstances, a strength of adhesion between the separator and the ionconductor layer passes the tape test according to the standard ASTMD3359-02.

In some embodiments involving the electrochemical cells described aboveand herein, the first electroactive material comprises lithium; e.g.,the first electroactive material may comprise lithium metal and/or alithium alloy. In some cases, the second electrode comprises sulfur as asecond electroactive material.

In some embodiments involving the electrochemical cells described aboveand herein, the ion conductor is deposited onto the separator byelectron beam evaporation or by a sputtering process.

In one set of embodiments, an electrochemical cell described herein is alithium-sulfur cell comprising a first electrode comprising lithium, asecond electrode comprising sulfur, a separator arranged between saidfirst electrode and said second electrode, and a solid ion conductorcontacting and/or bonded to the separator, wherein said solid ionconductor comprises a lithium-ion conducting oxysulfide.

In some embodiments involving the electrochemical cells described aboveand herein, said solid ion conductor comprises a lithium oxysulfide.

In some embodiments involving the electrochemical cells described aboveand herein, said solid ion conductor comprises a lithium oxysulfidehaving an atomic ratio of oxygen atoms to sulfur atoms (O:S) in therange of from 0.001:1 to 1.5:1, e.g., in the range of from 0.01:1 to0.25:1.

In some embodiments involving the electrochemical cells described aboveand herein, said solid ion conductor is in the form of a layer having athickness in the range of from 1 nm to 7 microns.

In some embodiments involving the electrochemical cells described aboveand herein, the separator is ionically conductive, the average ionicconductivity of the separator being preferably at least 10⁻⁷ S/cm at 25degrees Celsius.

In some embodiments involving the electrochemical cells described aboveand herein, said separator and said solid ion conductor contacting theseparator constitute a composite, the composite preferably having athickness of 5 microns to 40 microns. The composite may be, in someembodiments, a free-standing structure.

In some embodiments involving the electrochemical cells described aboveand herein, the strength of adhesion between said separator and saidsolid ion conductor contacting the separator is at least 350 N/m.

In some embodiments involving the electrochemical cells described aboveand herein, said solid ion conductor is placed against one of said firstand second electrodes. The solid ion conductor may be arranged toinhibit interaction of an electrolyte present in the electrochemicalcell with the electrode against which it is placed.

In some embodiments involving the electrochemical cells described aboveand herein, the solid ion conductor comprises an amorphous lithium-ionconducting oxysulfide, a crystalline lithium-ion conducting oxysulfideor a mixture of an amorphous lithium-ion conducting oxysulfide and acrystalline lithium-ion conducting oxysulfide, e.g., an amorphouslithium oxysulfide, a crystalline lithium oxysulfide, or a mixture of anamorphous lithium oxysulfide and a crystalline lithium oxysulfide.

In some embodiments involving the electrochemical cells described aboveand herein, the present invention relates to the use of a compositecapable of being arranged between a first electrode and a secondelectrode, the composite being constituted of a separator, and a solidion conductor contacting and/or bonded to the separator, wherein saidsolid ion conductor comprises a lithium-ion conducting oxysulfide, forseparating a first electrode and a second electrode of anelectrochemical cell, e.g., in a lithium sulfur cell. The solid ionconductor may be arranged for inhibiting interaction of an electrolytepresent in an electrochemical cell with one of said electrodes of saidelectrochemical cell.

In some embodiments involving the electrochemical cells described aboveand herein, the composite is constituted of a separator and a solid ionconductor contacting and/or being bond to the separator, wherein saidsolid ion conductor comprises a lithium-ion conducting oxysulfide.

In some embodiments involving the electrochemical cells described aboveand herein, the present invention further relates to a process of makingan electrochemical cell, comprising the following steps: making orproviding a separator, contacting and/or bonding to the separator asolid ion conductor, providing further building elements of theelectrochemical cell, and assembling the electrochemical cell.

In some embodiments involving the electrochemical cells described aboveand herein, contacting and/or bonding to the separator a solid ionconductor is achieved by depositing ion conductor material onto thesurface of the separator. In some embodiments involving theelectrochemical cells described above and herein, the intermediateproduct obtained by contacting and/or bonding to the separator a solidion conductor is a composite being a free-standing structure.

Specific features of aspects of the embodiments as defined above areillustrated or discussed herein below in more detail.

Other advantages and novel features of the present invention will becomeapparent from the following detailed description of various non-limitingembodiments of the invention when considered in conjunction with theaccompanying figures. In cases where the present specification and adocument incorporated by reference include conflicting and/orinconsistent disclosure, the present specification shall control.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the present invention will be described byway of example with reference to the accompanying figures, which areschematic and are not intended to be drawn to scale. In the figures,each identical or nearly identical component illustrated is typicallyrepresented by a single numeral. For purposes of clarity, not everycomponent is labeled in every figure, nor is every component of eachembodiment of the invention shown where illustration is not necessary toallow those of ordinary skill in the art to understand the invention. Inthe figures:

FIG. 1 is an exemplary schematic illustrations of electrochemical cellsincluding a composite structure comprising an ion conductor layer and aseparator layer, according to one set of embodiments.

FIG. 2 is an exemplary schematic illustration of, according to someembodiments, of a free-standing separator film comprising tortuous holepaths.

FIG. 3 is an exemplary schematic illustration of, according to someembodiments, of a porous separator coated with an ion conductor layer.

FIGS. 4A, 4B, and 4C are exemplary scanning electron microscopy (SEM)images of ceramic coatings deposited on a commercial separator.

FIG. 5 is a plot of air permeation time versus inorganic ion conductorthickness for various inorganic ion conductor-separator composites.

DETAILED DESCRIPTION

Composite structures including an ion-conducting material and apolymeric material (e.g., a separator) to protect electrodes aregenerally described. The ion-conducting material may be in the form of alayer that is bonded to a polymeric separator. The ion-conductingmaterial may comprise a lithium oxysulfide having a lithium-ionconductivity of at least at least 10⁻⁶ S/cm.

Layers of ceramic or other inorganic protective materials (e.g.,glasses, glassy-ceramics) have been used to protect electrodes (e.g.,lithium anodes) from adverse interaction with electrolyte materialduring operation of electrochemical cells. For example, protectedlithium anode (PLA) structures have been employed comprising alternatingcontinuous layers of ionically conductive ceramic and ionicallyconductive polymer. In certain cases, such protective electrodestructures can be ineffective. For example, the brittleness of theceramic, defects in the ceramic, and/or the swelling exhibited by thepolymer upon exposure to the electrolyte can cause the protectiveelectrode structure to crack or otherwise fail. The cascade failure ofthese layers can stem from the initial defects in the ceramic, which maybe present from handling and/or from processing. This in turn allows theelectrolyte to seep in and swell the polymer layer. The swelling of thislayer can break the ceramic layers below and the electrolyte penetratesfurther to swell more polymer layers. This can eventually destroy allthe protected layers, which can lead to failure of the electrochemicalcell.

One way to address the problems discussed above is to develop materialsand/or structures that do not substantially swell or break. This can bechallenging, however. For example, many known polymers, which areionically conductive, swell considerably in various electrochemical cellelectrolytes. Also, it can be difficult to process ceramic materialssuch that they do not contain defects, and handling of such materialswithout introducing defects (e.g., cracks) is difficult. The ceramicmaterial should also have sufficient ion conductivity to not inhibit ionconduction across the protective layer(s).

One approach described herein that can be used to address the issuesoutlined above with respect to ineffective electrode protectivestructures involves a structure that allows the use of a flexible,low-swelling polymer, which may be in the form of a separator, incombination with one or more ion conductor (e.g., a ceramic) layers thatinhibits electrolyte interaction with the electrode. At least one of theion conductor layer(s) may comprise a lithium oxysulfide material whichprovides sufficient ion conduction across the composite, as described inmore detail herein.

The separator can act as a smooth substrate to which a smooth, thin ionconductor layer can be deposited. Prior to deposition of the ionconductor layer, the surface of the separator may be treated to enhanceits surface energy. The increased surface energy of the separator canallow improved adhesion (e.g., bonding) between the ion conductor layerand the separator compared to when the surface of the separator is nottreated, as described below. As a result of increased adhesion betweenthe layers, the likelihood of delamination of the layers can be reduced,and the mechanical stability of the ion conductor layer can be improvedduring cycling of the cell. Additionally, since both the separator andthe ion conductor layer can be included in an electrochemical cell, theion conductor layer does not need to be released from a substrate. Theavoidance of releasing the ion conductor layer may, in some cases,improve the mechanical integrity of the ion conductor layer. In certainembodiments, the resulting ion conductor layer-separator composite canenhance the ion conductor layer's ability to withstand the mechanicalstresses encountered when it is placed in a pressurized cell against arough cathode.

Additionally, in certain structures involving the use of a flexibleseparator material, the structure can inhibit (and/or prevent)mechanical failure of other adverse mechanical impact, such as plasticdeformation, when changes in dimension are introduced to the structure,e.g., via swelling. The separator material may or may not be ionicallyconductive, which can allow for the use of a wide variety of separatormaterials (e.g., polymers that do or do not swell upon exposure toelectrolyte). By adopting designs with such spatial orientations of theion conductor and the separator, one can remove constraints on thematerials that are used, which can allow for the use of already existingmaterials. Other advantages are described in more detail below.

FIG. 1 is an exemplary cross-sectional schematic illustration of anelectrochemical cell comprising an ion conductor and a separator in theform of a composite structure, according to one set of embodiments. InFIG. 1, electrochemical cell 101 comprises first electrode 102 andsecond electrode 104. First electrode 102 (and/or second electrode 104)comprises an electroactive material. In certain embodiments, theelectroactive material in first electrode 102 comprises lithium. Firstelectrode 102 may be a negative electrode and second electrode 104 maybe a positive electrode.

In the exemplary embodiments of FIG. 1, electrochemical cell 101comprise a separator 106 between first electrode 102 and secondelectrode 104. Separator 106 may comprise pores 108 in which electrolytecan reside. The separator and an ion conductor 112 form a compositestructure, which may be bonded together and inhibit delamination orseparation of the layers, as described herein. Ion conductor 112 caninhibit interaction of electrolyte with the electroactive materialwithin electrode 102. In certain embodiments, ion conductor 112substantially prevents interaction of electrolyte with the electroactivematerial within electrode 102. Inhibiting or preventing the interactionof electrolyte with the electroactive material within electrode 102 canreduce or eliminate the degree to which electrode 102 is degraded orotherwise rendered inoperable by the electrolyte. Thus, in this fashion,ion conductor 112 can function as a protective structure within theelectrochemical cell.

It should be appreciated that while FIG. 1 shows an electrochemicalcell, in some embodiments not all components shown in the figure need bepresent. For instance, the articles and methods described herein mayencompass only components of electrochemical cells (e.g., a separatorand an ion conductor without one of an anode and/or cathode). It shouldalso be appreciated that other components that are not shown in FIG. 1may be included in electrochemical cells in some embodiments. As oneexample, an ion conductor layer (e.g., an inorganic layer ion conductorlayer) may be a part of a multi-layered structure comprising more thanone ion conductor layers. At least two layers (e.g., two ion conductorlayers) of the multi-layered structure may be formed of differentmaterials, or the same material. In some cases, at least one of thelayers of the multi-layered structure may comprise a lithium oxysulfidematerial, as described in more detail below. Other configurations arealso possible.

It should be understood that, everywhere in which lithium is describedas an electroactive material, other suitable electroactive materials(including others described elsewhere herein) could be substituted. Inaddition, everywhere in which a ceramic is described as the ionconductor, other ion conductor materials (including others describedelsewhere herein) could be used.

As described herein, a free-standing, porous, separator layer may beused as the polymer matrix on which an ion conductor layer is deposited.According to one exemplary fabrication process, a porous, separatorlayer 500 is provided, as illustrated in FIG. 2. The porous separatorlayer may be conductive or non-conductive to ions. One example of asuitable film is a commercially available porous, separator layer, suchas those used in battery separators. The hole pathways through the layercan be quite tortuous in some embodiments. In certain embodiments, thehole pathways through the layer pass completely through the layer. Thisfree standing layer can then be coated with an ion conductor (e.g., aceramic such as a lithium oxysulfide).

The approach of coating a free-standing separator with an ion conductormaterial offers a number of advantages over methods of fabricating otherprotective structures. First among these is the fact that the resultingstructure does not have to be released from a carrier substrate. Thisnot only results in a cost savings and a reduction of materials, but itavoids the possibility of damaging the fragile ion conductor coatingduring the release step. Second, binding the ion conductor material tothe surface of the separator creates a mechanically stable platform forthin ion conductor (e.g., ceramic) coatings, greatly enhancing thecoating's ability to withstand the mechanical stresses encountered whenit is placed in a pressurized cell against a rough cathode. Third, sucha process can be accomplished in a single chamber pump down. Not havingto open the vacuum chamber during the deposition process reduces thechances for contamination as well as minimizes the handling of thematerial.

As described herein, in some embodiments an ion conductor material canbe deposited onto a separator layer using a vacuum deposition process(e.g., sputtering, CVD, thermal or E-beam evaporation). Vacuumdeposition can permit the deposition of smooth, dense, and homogenousthin layers. In some embodiments it is desirable to deposit thin layersof an inorganic ion conductor material since thick layers can increasethe internal resistance of the battery, lowering the battery ratecapability and energy density.

As shown illustratively in structure 504 in FIG. 3, the pores of aseparator layer 500 (e.g., a separator) are substantially unfilled withan ion conductor 505 (e.g., ceramic). In embodiments in which all orportions of the pores of the separator layer are unfilled with aninorganic ion conductor (e.g., a ceramic), those portions may be filledwith an electrolyte solvent when positioned in an electrochemical cell.In some embodiments, the ion conductor may be coated with a final layerof an electroactive material 510 (e.g., lithium). The electroactivematerial layer can be configured to adhere to the ion conductive layer,as described in more detail below. In certain embodiments of thisprocess, there is no etching involved, which can make the process veryfast and efficient.

It should also be appreciated that although several figures shown hereinillustrate a single ion conductor layer, in some embodiments aprotective structure includes multiple ion conductor layers (e.g., atleast 2, 3, 4, 5, or 6 ion conductor layers) to form a multi-layeredstructure. As one example, an ion conductor layer (e.g., an inorganiclayer ion conductor layer) may be a part of a multi-layered structurecomprising more than one ion conductor layers, wherein at least twolayers (e.g., two ion conductor layers) of the multi-layered structureare formed of different materials. In other instances, at least twolayers of the multi-layered structure (e.g., two ion conductor layers)are formed of the same material. In some cases, at least one of thelayers of the multi-layered structure may comprise a lithium oxysulfidematerial. The multi-layered structure may optionally include polymerlayers (e.g., at least 1, 2, 3, 4, 5, or 6 polymer layers). In someembodiments, the polymer layers are interspersed between two or more ionconductor layers. Each of the layers of the multi-layered structure mayindependently have features (e.g., thickness, conductivity, bulkelectronic resistivity) described generally herein for the ion conductorlayer and/or polymer layer.

In structures involving a single ion conductor layer, the ion conductorlayer (which may comprise a lithium oxysulfide in some embodiments) maybe in direct contact with each an electroactive material of a firstelectrode and the separator layer.

As described herein, in some embodiments involving the formation of aprotective structure by disposing an ion conductor on the surface of aseparator layer, it is desirable to increase the bonding or adhesivestrength between the ion conductor and the separator layer. As a resultof increased adhesion between the layers, the likelihood of delaminationof the layers can be reduced and the mechanical stability of the ionconductor layer can be improved during cycling of the cell. For example,the resulting ion conductor layer-separator composite can enhance theion conductor layer's ability to withstand the mechanical stressesencountered when it is placed in a pressurized cell against a roughcathode. Accordingly, in some embodiments, prior to deposition of theion conductor layer, the surface of the separator layer may be treated(e.g., in a pre-treatment process) to enhance the surface energy of theseparator layer. The increased surface energy of the separator layer canallow improved adhesion between the ion conductor layer and theseparator compared to when the surface of the separator is not treated.

In certain embodiments, adhesion is enhanced when a ratio of thethickness of the ion conductor layer to the average pore diameter of theseparator is present in certain ranges, as described in more detailbelow.

To increase the surface energy of the separator layer (i.e., activatethe surface of the separator layer), a variety of methods may be used.The method may involve, for example, a pre-treatment step in which thesurface of the separator is treated prior to deposition of an ionconductor material. In certain embodiments, activation or apre-treatment step involves subjecting the separator to a source ofplasma. For example, an anode layer ion source (ALS) may be used togenerate a plasma. In general, an anode layer ion source involvesgenerating electrons by an applied potential in the presence of aworking gas. The resulting plasma generated creates additional ions andelectrons, which accelerate towards the target substrate (e.g., theseparator layer), providing ion bombardment of a substrate. Thisbombardment of the separator layer substrate increases the surfaceenergy of the separator layer and promotes adhesion between theseparator and the ion conductor material to follow.

Various working gases can be used during a surface activation processsuch as plasma treatment. In general, surface activation may occur inthe presence of one or more gases including: air, oxygen, ozone, carbondioxide, carbonyl sulfide, sulfur dioxide, nitrous oxide, nitric oxide,nitrogen dioxide, nitrogen, ammonia, hydrogen, freons (e.g., CF₄,CF₂Cl₂, CF₃Cl), silanes (e.g., SiH₄, SiH₂(CH₃)₂, SiH₃CH₃), and/or argon.

In general, plasma treatment modifies the surface of the separator byionizing the working gas and/or surface and, in some instances, formingor depositing activated functional chemical groups onto the surface. Incertain embodiments, activation of certain functional groups on thesurface of the separator layer may promote binding between the separatorlayer and an ion conductor material. In certain embodiments, theactivated functional groups may include one or more of the following:carboxylates (e.g., —COOH), thiols (e.g., —SH), alcohols (e.g., —OH),acyls (e.g., —CO), sulfonics and/or sulfonic acids (e.g., —SOOH or—SO₃H), amines (e.g., —NH₂), nitric oxides (e.g., —NO), nitrogendioxides (e.g., —NO₂), chlorides (e.g., —Cl), haloalkyl groups (e.g.,CF₃), silanes (e.g., SiH₃), and/or organosilanes (SiH₂CH₃). Otherfunctional groups are also possible.

In certain embodiments, plasma treatment, such as an ALS process, isperformed in a chamber at a pressure ranging between, for example, 10⁻²to 10⁻⁸ Torr. For instance, the pressure may be greater than or equal to10⁻⁸ Torr, greater than or equal to 10⁻⁷ Torr, greater than or equal to10⁻⁶ Torr, greater than or equal to 10⁻⁵ Torr, greater than or equal to10⁻⁴ Torr, or greater than or equal to 10⁻³ Torr. The pressure may beless than or equal to 10⁻² Torr, less than or equal to 10⁻³ Torr, lessthan or equal to 10⁻⁴ Torr, less than or equal to 10⁻⁵ Torr, or lessthan or equal to 10⁻⁶ Torr. Combinations of the above-referenced rangesare also possible.

Plasma treatment may generally be performed with a power of the ionsource ranging between, for example, 5 W to 200 W. For instance, thepower may be greater than or equal to 5 W, great than or equal to 10 W,greater than or equal to 20 W, greater than or equal to 50 W, greaterthan or equal to 100 W, or greater than or equal to 200 W. The power maybe less than or equal to 200 W, or less than or equal to 100 W, or lessthan or equal to 50 W, or less than or equal to 20 W, or less than orequal to 5 W. Combinations of the above-referenced power ranges are alsopossible.

Actual surface energy enhancement is a function of pressure, power, andexposure time, with care taken not to overexpose the material which canlead to thermal damage. For example, the exposure time (i.e., the timefor which the separator layer is subjected to plasma treatment) may begreater than or equal to 1 second, greater than or equal to 10 seconds,greater than or equal to 30 seconds, greater than or equal to 1 minute,greater than or equal to 2 minutes, greater than or equal to 5 minutes,greater than or equal to 10 minutes, greater than or equal to 20minutes, greater than or equal to 30 minutes, greater than or equal to 1hour, or greater than or equal to 5 hours. The exposure time may be lessthan or equal to 10 hours, less than or equal to 1 hour, less than orequal to 30 minutes, less than or equal to 10 minutes, less than orequal to 5 minutes, less than or equal to 1 minute, less than or equalto 10 seconds, or less than or equal to 1 second. Combinations of theabove-referenced exposure times are also possible.

It would be appreciable to those skilled in the art that setupconditions can vary depending on the efficiency of the plasma system,the efficiency of the power supply, RF matching issues, gas distributionand selection, distance from target substrate, time of plasma exposure,etc. Thus, various combinations of power at which the plasma source isoperated, the operating pressure, gas selection, and the length of timeof exposure to the plasma source are possible.

Although plasma treatment is primarily described for increasing thesurface energy of a substrate (e.g., a separator), other methods forincreasing the surface energy of a substrate are also possible. Forexample, in certain embodiments, flame surface treatment, coronatreatment, chemical treatment, surface oxidation, absorption offunctional groups to the surface, and/or surface grafting may be used toincrease the surface energy of a substrate.

The surface energy of the separator layer can be increased to anysuitable value. In some embodiments, the surface energy of the separatorlayer before treatment may be, for example, between 0 and 50 dynes. Forexample, the surface energy may be at least 0 dynes, at least 10 dynes,at least 20 dynes, at least 30 dynes, at least 40 dynes, or at least 50dynes. The surface energy may be less than 50 dynes, less than 40 dynes,less than 30 dynes, less than 20 dynes, or less than 10 dynes.Combinations of the above-referenced ranges are also possible.

In some embodiments, the surface energy of the separator layer aftertreatment may range from, for example, between 30 dynes and 100 dynes (1dyne=1 g·cm/s²=10⁻⁵ kg·m/s²=10⁻⁵ N). In certain embodiments, the surfaceenergy of the separator layer after treatment may be at least 30 dynes,at least 40 dynes, at least 50 dynes, at least 60 dynes, at least 70dynes, at least 80 dynes, at least 90 dynes. The surface energy aftertreatment may be, for example, less than 100 dynes, less than 90 dynes,less than 80 dynes, less than 70 dynes, less than 60 dynes, or less than50 dynes. Combinations of the above-referenced ranges are also possible.Other surface energies are also possible.

In certain embodiments, the surface energy of a separator surface beforetreatment can be increased at least 1.2 times, at least 1.5 times, atleast 2 times, at least 3 times, at least 5 times, at least 10 times, atleast 20 times, at least 50 times, at least 70 times, at least 100 timesafter treatment. In some cases, the surface treatment may be increasedup to 500 times after treatment. Other increases in surface energy arealso possible.

As described herein, in some embodiments treatment of a surface resultsin chemical and/or physical bonds between an ion conductor and aseparator layer being formed. In some embodiments, the bonds may includecovalent bonds. Additionally or alternatively, non-covalent interactions(e.g., hydrophobic and/or hydrophilic interactions, electrostaticinteractions, van der Waals interactions) may be formed. Generally,treatment (e.g., pre-treatment) of a surface resulting in bond formationincreases the degree of adhesion between two layers compared to theabsence of such treatment.

To determine relative adhesion strength between two layers, a tape testcan be performed. Briefly, the tape test utilizes pressure-sensitivetape to qualitatively assess the adhesion between a first layer (e.g., aseparator layer) and a second layer (e.g., a ion conducting layer). Insuch a test, an X-cut can be made through the first layer (e.g.,separator layer) to the second layer (e.g., ion conducting layer).Pressure-sensitive tape can be applied over the cut area and removed. Ifthe separator layer stays on the ion conducting layer (or vice versa),adhesion is good. If the separator layer comes off with the strip oftape, adhesion is poor. The tape test may be performed according to thestandard ASTM D3359-02. In some embodiments, a strength of adhesionbetween the separator and the inorganic ion conductor layer passes thetape test according to the standard ASTM D3359-02, meaning the ionconductor layer does not delaminate from the separator layer during thetest. In some embodiments, the tape test is performed after the twolayers (e.g., a first layer such as a separator layer, to a second layersuch as an ion conducting layer) have been included in a cell, such as alithium-sulfur cell or any other appropriate cell described herein, thathas been cycled at least 5 times, at least 10 times, at least 15 times,at least 20 times, at least 50 times, or at least 100 times, and the twolayers pass the tape test after being removed from the cell (e.g., thefirst layer does not delaminate from the second layer during the test).

The peel test may include measuring the adhesiveness or force requiredto remove a first layer (e.g., a separator layer) from a unit length ofa second layer (e.g., a ion conducting layer), which can be measured inN/m, using a tensile testing apparatus or another suitable apparatus.Such experiments can optionally be performed in the presence of asolvent (e.g., an electrolyte) or other components to determine theinfluence of the solvent and/or components on adhesion.

In some embodiments, the strength of adhesion between two layers (e.g.,a first layer such as a separator layer and a second layer such as anion conductor layer) may be increased as a result of a treatment (e.g.,pre-treatment) step described herein. The strength of adhesion aftertreatment may range, for example, between 100 N/m to 2000 N/m. Incertain embodiments, the strength of adhesion may be at least 50 N/m, atleast 100 N/m, at least 200 N/m, at least 350 N/m, at least 500 N/m, atleast 700 N/m, at least 900 N/m, at least 1000 N/m, at least 1200 N/m,at least 1400 N/m, at least 1600 N/m, or at least 1800 N/m. In certainembodiments, the strength of adhesion may be less than or equal to 2000N/m, less than or equal to 1500 N/m, less than or equal to 1000 N/m,less than or equal to 900 N/m, less than or equal to 700 N/m, less thanor equal to 500 N/m, less than or equal to 350 N/m, less than or equalto 200 N/m, less than or equal to 100 N/m, or less than or equal to 50N/m. Other strengths of adhesion are also possible.

As described herein, the relative thickness of the ion conductor layerto the average pore diameter of the separator layer may influence thedegree of adhesive strength or bonding between the two layers in acomposite. For instance, in some cases the thickness of the ionconductor layer may be greater than the average pore diameter (orlargest pore diameter) of separator layer, which results in theformation of a smooth, dense, and homogenous ion conductor layer thatresists delamination from separator layer.

As described herein, in an electrochemical cell, the ion conductor layermay serve as a solvent barrier which acts to prevent or reduce thelikelihood of a liquid electrolyte from interacting with anelectroactive material (e.g., lithium metal). In some embodiments, theability of the composite ion conductor layer-separator to act as abarrier can be measured in part by an air permeation test (e.g., theGurley Test). The Gurley Test determines the time required for aspecific volume of air to flow through a standard area of the material.As such, larger air permeation times (Gurley-sec) generally correspondto better barrier properties.

One of ordinary skill in the art may have expected that improved barrierproperties (e.g., higher air permeation times) would be achieved byusing relatively thicker inorganic ion conductor layers, since thickerlayers may be more difficult for fluids to penetrate across the layer.However, as described in more detail below, the inventors observed thata reduced thickness of the ion conductor layer in an inorganic ionconductor layer-separator composite resulted in an improvement inbarrier properties, as measured by an increase in air permeation timeusing the Gurley Test, compared to inorganic ion conductorlayer-separator composites having relatively thicker inorganic ionconductor layers (see Example 3 and FIG. 5). Additionally, thecombination of a thin inorganic ion conductor layer and a plasma treatedseparator showed the highest air permeation time (and, therefore,enhanced barrier properties), compared to composites that did notinclude a plasma treated separator, or a composite that had a relativelythicker inorganic ion conductor layer. Without wishing to be bound byany theory, the inventors believe that high permeation times, andtherefore good barrier properties, are contributed in part by goodstrength of adhesion between the two layers and good mechanicalflexibility (i.e., lower film stresses) of the ion conductor layer so asto reduce the likelihood of cracking of the layer. Cracking of the ionconductor layer, similar to delamination between layers, typicallyresults in poorer barrier properties.

In some embodiments, air permeation times of a composite describedherein (e.g., an ion conductor layer-separator composite) may be atleast 1,000 Gurley-s, at least 5,000 Gurley-s, at least 10,000 Gurley-s,at least 20,000 Gurley-s, at least 40,000 Gurley-s, at least 60,000Gurley-s, at least 80,000 Gurley-s, at least 100,000 Gurley-s, at least120,000 Gurley-s, at least 140,000 Gurley-s, at least 160,000 Gurley-s,at least 180,000 Gurley-s, at least 200,000 Gurley-s, at least 500,000Gurley-s, or at least 10⁶ Gurley-s. In some embodiments, the compositeis substantially impermeable. In some embodiments, the air permeationtime may be less than or equal to 10⁶ Gurley-s, less than or equal to500,000 Gurley-s, less than or equal to 200,000 Gurley-s, less than orequal to 150,000 Gurley-s, less than or equal to 120,000 Gurley-s, lessthan or equal to 80,000 Gurley-s, less than or equal to 40,000 Gurley-s,less than or equal to 20,000 Gurley-s, less than or equal to 10,000Gurley-s, or less than or equal to 5,000 Gurley-s. The air permeationtimes and Gurley tests described herein refer to those performedaccording to TAPPI Standard T 536 om-12, which involves a pressuredifferential of 3 kPa and a sample size of a square inch.

An ion conductor or ion conductor layer described herein can be formedof a variety of types of materials. In certain embodiments, the materialfrom which the ion conductor is formed may be selected to allow ions(e.g., electrochemically active ions, such as lithium ions) to passthrough the ion conductor but to substantially impede electrons frompassing across the ion conductor. By “substantially impedes”, in thiscontext, it is meant that in this embodiment the material allows lithiumion flux at least ten times greater than electron passage.

In some embodiments, the material used for an ion conductor layer has ahigh enough conductivity (e.g., at least 10⁻⁶ S/cm, or anotherconductivity value described herein) in its first amorphous state. Thematerial may also be chosen for its ability to form a smooth, dense andhomogenous thin films, especially on a polymer layer such as aseparator. Lithium oxysulfides may especially include thesecharacteristics.

The ion conductor can be configured to be electronically non-conductive,in certain embodiments, which can inhibit the degree to which the ionconductor causes short circuiting of the electrochemical cell. Incertain embodiments, all or part of the ion conductor can be formed of amaterial with a bulk electronic resistivity of at least about 10⁴Ohm-meters, at least about 10⁵ Ohm-meters, at least about 10¹⁰Ohm-meters, at least about 10¹⁵ Ohm-meters, or at least about 10²⁰Ohm-meters. The bulk electronic resistivity may be, in some embodiments,less than or equal to about 10²⁰ Ohm-meters, or less than or equal toabout 10¹⁵ Ohm-meters. Combinations of the above-referenced ranges arealso possible. Other values of bulk electronic resistivity are alsopossible.

In some embodiments, the average ionic conductivity (e.g., lithium ionconductivity) of the ion conductor material is at least about 10⁻⁷ S/cm,at least about 10⁻⁶ S/cm, at least about 10⁻⁵ S/cm, at least about 10⁻⁴S/cm, at least about 10⁻³ S/cm, at least about 10⁻² S/cm, at least about10⁻¹ S/cm, at least about 1 S/cm, or at least about 10 S/cm. The averageionic conductivity may less than or equal to about 20 S/cm, less than orequal to about 10 S/cm, or less than or equal to 1 S/cm. Conductivitymay be measured at room temperature (e.g., 25 degrees Celsius).

In some embodiments, the ion conductor can be a solid. In someembodiments, the ion conductor comprises or may be substantially formedof a non-polymeric material. For example, the ion conductor may compriseor may be substantially formed of an inorganic material.

Although a variety of materials can be used as an ion conductive layer,in one set of embodiments, the ion conductor layer is an inorganic ionconductive layer. For example, the inorganic ion conductor layer may bea ceramic, a glass, or a glassy-ceramic. In some embodiments, the ionconductor comprises an oxysulfide such as lithium oxysulfide.

In certain embodiments in which an inorganic ion conductor materialdescribed herein comprises a lithium oxysulfide, the lithium oxysulfide(or an ion conductor layer comprising a lithium oxysulfide) may have anoxide content between 0.1-20 wt %. The oxide content may be measuredwith respect to the total weight of the lithium oxysulfide material orthe total weight of the ion conductor layer that comprises the lithiumoxysulfide material. For instance, the oxide content may be at least 0.1wt %, at least 1 wt %, at least 2 wt %, at least 5 wt %, at least 10 wt%, %, at least 15 wt %, or at least 20 wt %. In some embodiments, theoxide content may be less than or equal to 20 wt %, less than or equalto 15 wt %, less than or equal to 10 wt %, less than or equal to 5 wt %,less than or equal to 2 wt %, or less than or equal to 1 wt % of thelithium oxysulfide. Combinations of the above-noted ranges are alsopossible. The elemental composition, including oxide content, of a layermay be determined by methods such as energy-dispersive X-rayspectroscopy.

In some embodiments in which an inorganic ion conductor materialdescribed herein comprises a lithium oxysulfide, the lithium oxysulfidematerial (or an ion conductor layer comprising a lithium oxysulfide) hasan atomic ratio of sulfur atoms to oxygen atoms (S:O) of between, forexample, 1:1 to 1000:1. For instance, the atomic ratio between sulfuratoms to oxygen atoms (S:O) in the lithium oxysulfide material (or anion conductor layer comprising a lithium oxysulfide) may be at least0.5:1, at least 0.667:1, at least 1:1, at least 2:1, at least 3:1, atleast 4:1, at least 5:1, at least 10:1, at least 20:1, at least 50:1, atleast 70:1, at least 90:1, at least 100:1, at least 200:1, at least500:1, or at least 1000:1. The atomic ratio of sulfur atoms to oxygenatoms (S:O) in the lithium oxysulfide material (or an ion conductorlayer comprising a lithium oxysulfide) may be less than or equal to1000:1, less than or equal to 500:1, less than or equal to 200:1, lessthan or equal to 100:1, less than or equal to 90:1, less than or equalto 70:1, less than or equal to 50:1, less than or equal to 20:1, lessthan or equal to 10:1, less than or equal to 5:1, less than or equal to3:1, or less than or equal to 2:1. Combinations of the above-notedranges are also possible (e.g., an atomic ratio of S:O of between 2:1 to1000:1, or between 4:1 to 100:1). Other ranges are also possible. Theelemental composition of a layer may be determined by methods such asenergy-dispersive X-ray spectroscopy.

It should be noted that the atomic ratio may also be expressed as aratio of oxygen atoms to sulfur atoms (O:S) and that the reverse of theabove-noted ratios may be applicable. For instance, in some embodimentsthe lithium oxysulfide material (or an ion conductor layer comprising alithium oxysulfide) comprises a lithium oxysulfide having an atomicratio of oxygen atoms to sulfur atoms (O:S) in the range of from 0.001:1to 1.5:1, e.g., in the range of from 0.01:1 to 0.25:1.

In some embodiments, a lithium oxysulfide material described herein mayhave a formula of x(yLi₂S+zLi₂O)+MS₂ (where M is Si, Ge, or Sn), wherey+z=1, and where x may range from 0.5-3. In certain embodiments, x is atleast 0.5, at least 1.0, at least 1.5, at least 2.0, or at least 2.5. Inother embodiments, x is less than or equal to 3.0, less than or equal to2.5, less than or equal to 2.0, less than or equal to 1.5, less than orequal to 1.0, or less than or equal to 0.5. Combinations of theabove-noted ranges are also possible. Other values for x are alsopossible.

The ion conductor may comprise, in some embodiments, an amorphouslithium-ion conducting oxysulfide, a crystalline lithium-ion conductingoxysulfide or a mixture of an amorphous lithium-ion conductingoxysulfide and a crystalline lithium-ion conducting oxysulfide, e.g., anamorphous lithium oxysulfide, a crystalline lithium oxysulfide, or amixture of an amorphous lithium oxysulfide and a crystalline lithiumoxysulfide.

In some embodiments, the inorganic ion conductor, such as a lithiumoxysulfide described above, comprises a glass forming additive rangingfrom 0 wt % to 30 wt % of the inorganic ion conductor material. Examplesof glass forming additives include, for example, SiO₂, Li₂SiO₃, Li₄SiO₄,Li₃PO₄, LiPO₃, Li₃PS₄, LiPS₃, B₂O₃, B₂S₃. Other glass forming additivesare also possible. In certain embodiments, glass forming additives maybe at least 5 wt %, at least 10 wt %, at least 15 wt %, at least 20 wt%, at least 25 wt %, or at least 30 wt % of the inorganic ion conductormaterial. In certain embodiments, glass forming additives may be lessthan or equal to 30 wt %, less than or equal to 25 wt %, less than orequal to 20 wt %, less than or equal to 15 wt %, or less than or equalto 10 wt % of the inorganic ion conductor material. Combinations of theabove-noted ranges are also possible. Other values of glass formingadditives are also possible.

In some embodiments, one or more additional salts (e.g., lithium saltssuch as LiI, LiBr, LiCl, Li₂CO₃, or Li₂SO₄) may be added to theinorganic ion conductor material at a range of, e.g., 0 to 50 mol %.Other salts are also possible. In certain embodiments, additional saltsare at least 0 mol %, at least 10 mol %, at least 20 mol %, at least 30mol %, at least 40 mol %, or at least 50 mol %. In certain embodiments,additional salts are less than or equal to 50 mol %, less than or equalto 40 mol %, less than or equal to 30 mol %, less than or equal to 20mol %, or less than or equal to 10 mol %. Combinations of theabove-noted ranges are also possible. Other values of mol % are alsopossible.

Additional examples of ion conductors include lithium nitrides, lithiumsilicates, lithium borates, lithium aluminates, lithium phosphates,lithium phosphorus oxynitrides, lithium silicosulfides, lithiumgermanosulfides, lithium oxides (e.g., Li₂O, LiO, LiO₂, LiRO₂, where Ris a rare earth metal), lithium lanthanum oxides, lithium titaniumoxides, lithium borosulfides, lithium aluminosulfides, and lithiumphosphosulfides, and combinations thereof.

In certain embodiments, the ion conductor is formed of a single-ionconductive material (e.g., a single-ion conductive ceramic material).

Those of ordinary skill in the art, given the present disclosure, wouldbe capable of selecting appropriate materials for use as the ionconductor. Relevant factors that might be considered when making suchselections include the ionic conductivity of the ion conductor material;the ability to deposit or otherwise form the ion conductor material onor with other materials in the electrochemical cell; the brittleness ofthe ion conductor material; the compatibility of the ion conductormaterial with the polymer or separator material; the compatibility ofthe ion conductor material with the electrolyte of the electrochemicalcell; the ion conductivity of the material (e.g., lithium ionconductivity); and/or the ability to adhere the ion conductor to theseparator material.

The ion conductor material may be deposited by any suitable method suchas sputtering, electron beam evaporation, vacuum thermal evaporation,laser ablation, chemical vapor deposition (CVD), thermal evaporation,plasma enhanced chemical vacuum deposition (PECVD), laser enhancedchemical vapor deposition, and jet vapor deposition. The technique usedmay depend on the type of material being deposited, the thickness of thelayer, etc.

As described herein, in certain preferred embodiments, an ion conductormaterial can be deposited onto a separator using a vacuum depositionprocess (e.g., sputtering, CVD, thermal or E-beam evaporation). Vacuumdeposition can permit the deposition of smooth, dense, and homogenousthin layers.

In embodiments in which the ion conductor is in the form of a layer(e.g., a layer adjacent and/or attached to a polymer layer (e.g., aseparator)), the thickness of the ion conductor layer may vary. Thethickness of an ion conductor layer may vary over a range from, forexample, 1 nm to 7 microns. For instance, the thickness of the ionconductor layer may be between 1-10 nm, between 10-100 nm, between 10-50nm, between 30-70 nm, between 100-1000 nm, or between 1-7 microns. Thethickness of an ion conductor layer may, for example, be less than orequal to 7 microns, less than or equal to 5 microns, less than or equalto 2 microns, less than or equal to 1000 nm, less than or equal to 600nm, less than or equal to 500 nm, less than or equal to 250 nm, lessthan or equal to 100 nm, less than or equal to 70 nm, less than or equalto 50 nm, less than or equal to 25 nm, or less than or equal to 10 nm.In some embodiments, an ion conductor layer is at least 10 nm thick, atleast 20 nm thick, at least 30 nm thick, at least 100 nm thick, at least400 nm thick, at least 1 micron thick, at least 2.5 microns thick, or atleast 5 microns thick. Other thicknesses are also possible. Combinationsof the above-noted ranges are also possible.

As described herein, the methods and articles provided herein may allowthe formation of smooth surfaces. In some embodiments, the RMS surfaceroughness of an ion conductor layer of a protective structure may be,for example, less than 1 μm. In certain embodiments, the RMS surfaceroughness for such surfaces may be, for example, between 0.5 nm and 1 μm(e.g., between 0.5 nm and 10 nm, between 10 nm and 50 nm, between 10 nmand 100 nm, between 50 nm and 200 nm, between 10 nm and 500 nm). In someembodiments, the RMS surface roughness may be less than or equal to 0.9μm, less than or equal to 0.8 μm, less than or equal to 0.7 μm, lessthan or equal to 0.6 μm, less than or equal to 0.5 μm, less than orequal to 0.4 μm, less than or equal to 0.3 μm, less than or equal to 0.2μm, less than or equal to 0.1 μm, less than or equal to 75 nm, less thanor equal to 50 nm, less than or equal to 25 nm, less than or equal to 10nm, less than or equal to 5 nm, less than or equal to 2 nm, less than orequal to 1 nm. In some embodiments, the RMS surface roughness may begreater than 1 nm, greater than 5 nm, greater than 10 nm, greater than50 nm, greater than 100 nm, greater than 200 nm, greater than 500 nm, orgreater than 700 nm. Other values are also possible. Combinations of theabove-noted ranges are also possible (e.g., a RMS surface roughness ofless than or equal to 0.5 μm and greater than 10 nm. A polymer layer ofa protective structure may have a RMS surface roughness of one or moreof the ranges noted above.

The separator can be configured to inhibit (e.g., prevent) physicalcontact between a first electrode and a second electrode, which couldresult in short circuiting of the electrochemical cell. The separatorcan be configured to be substantially electronically non-conductive,which can inhibit the degree to which the separator causes shortcircuiting of the electrochemical cell. In certain embodiments, all orportions of the separator can be formed of a material with a bulkelectronic resistivity of at least about 10⁴, at least about 10⁵, atleast about 10¹⁰, at least about 10¹⁵, or at least about 10²⁰Ohm-meters. Bulk electronic resistivity may be measured at roomtemperature (e.g., 25 degrees Celsius).

In some embodiments, the separator can be ionically conductive, while inother embodiments, the separator is substantially ionicallynon-conductive. In some embodiments, the average ionic conductivity ofthe separator is at least about 10⁻⁷ S/cm, at least about 10⁻⁶ S/cm, atleast about 10⁻⁵ S/cm, at least about 10⁻⁴ S/cm, at least about 10⁻²S/cm, at least about 10⁻¹ S/cm. In certain embodiments, the averageionic conductivity of the separator may be less than or equal to about 1S/cm, less than or equal to about 10⁻¹ S/cm, less than or equal to about10⁻² S/cm, less than or equal to about 10⁻³ S/cm, less than or equal toabout 10⁻⁴ S/cm, less than or equal to about 10⁻⁵ S/cm, less than orequal to about 10⁻⁶ S/cm, less than or equal to about 10⁻⁷ S/cm, or lessthan or equal to about 10⁻⁸ S/cm. Combinations of the above-referencedranges are also possible (e.g., an average ionic conductivity of atleast about 10⁻⁸ S/cm and less than or equal to about 10⁻¹ S/cm).

In some embodiments, the separator can be a solid. The separator may beporous to allow an electrolyte solvent to pass through it. In somecases, the separator does not substantially include a solvent (like in agel), except for solvent that may pass through or reside in the pores ofthe separator. In other embodiments, a separator may be in the form of agel.

In certain embodiments, a separator may comprise a mixture of apolymeric binder, which may include one or more polymeric materialsdescribed herein (e.g., the polymers listed below for the separator),and a filler comprising a ceramic or a glassy/ceramic material, such asa material described herein for an ion conductor layer.

A separator as described herein can be made of a variety of materials.The separator may be polymeric in some instances, or formed of aninorganic material (e.g., glass fiber filter papers) in other instances.Examples of suitable separator materials include, but are not limitedto, polyolefins (e.g., polyethylenes, poly(butene-1), poly(n-pentene-2),polypropylene, polytetrafluoroethylene), polyamines (e.g., poly(ethyleneimine) and polypropylene imine (PPI)); polyamides (e.g., polyamide(Nylon), poly(e-caprolactam) (Nylon 6), poly(hexamethylene adipamide)(Nylon 66)), polyimides (e.g., polyimide, polynitrile, andpoly(pyromellitimide-1,4-diphenyl ether) (Kapton®) (NOMEX®) (KEVLAR®));polyether ether ketone (PEEK); vinyl polymers (e.g., polyacrylamide,poly(2-vinyl pyridine), poly(N-vinylpyrrolidone),poly(methylcyanoacrylate), poly(ethylcyanoacrylate),poly(butylcyanoacrylate), poly(isobutylcyanoacrylate), poly(vinylacetate), poly (vinyl alcohol), poly(vinyl chloride), poly(vinylfluoride), poly(2-vinyl pyridine), vinyl polymer, polychlorotrifluoroethylene, and poly(isohexylcynaoacrylate)); polyacetals; polyesters(e.g., polycarbonate, polybutylene terephthalate, polyhydroxybutyrate);polyethers (poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO),poly(tetramethylene oxide) (PTMO)); vinylidene polymers (e.g.,polyisobutylene, poly(methyl styrene), poly(methylmethacrylate) (PMMA),poly(vinylidene chloride), and poly(vinylidene fluoride)); polyaramides(e.g., poly(imino-1,3-phenylene iminoisophthaloyl) andpoly(imino-1,4-phenylene iminoterephthaloyl)); polyheteroaromaticcompounds (e.g., polybenzimidazole (PBI), polybenzobisoxazole (PBO) andpolybenzobisthiazole (PBT)); polyheterocyclic compounds (e.g.,polypyrrole); polyurethanes; phenolic polymers (e.g.,phenolformaldehyde); polyalkynes (e.g., polyacetylene); polydienes(e.g., 1,2-polybutadiene, cis or trans-1,4-polybutadiene); polysiloxanes(e.g., poly(dimethylsiloxane) (PDMS), poly(diethylsiloxane) (PDES),polydiphenylsiloxane (PDPS), and polymethylphenylsiloxane (PMPS)); andinorganic polymers (e.g., polyphosphazene, polyphosphonate, polysilanes,polysilazanes). In some embodiments, the polymer may be selected frompoly(n-pentene-2), polypropylene, polytetrafluoroethylene, polyamides(e.g., polyamide (Nylon), poly(ε-caprolactam) (Nylon 6),poly(hexamethylene adipamide) (Nylon 66)), polyimides (e.g.,polynitrile, and poly(pyromellitimide-1,4-diphenyl ether) (Kapton®)(NOMEX®) (KEVLAR®)), polyether ether ketone (PEEK), and combinationsthereof.

The mechanical and electronic properties (e.g., conductivity,resistivity) of these polymers are known. Accordingly, those of ordinaryskill in the art can choose suitable materials based on their mechanicaland/or electronic properties (e.g., ionic and/or electronicconductivity/resistivity), and/or can modify such polymers to beionically conducting (e.g., conductive towards single ions) based onknowledge in the art, in combination with the description herein. Forexample, the polymer materials listed above and herein may furthercomprise salts, for example, lithium salts (e.g., LiSCN, LiBr, LiI,LiClO₄, LiAsF₆, LiSO₃CF₃, LiSO₃CH₃, LiBF₄, LiB(Ph)₄, LiPF₆,LiC(SO₂CF₃)₃, and LiN(SO₂CF₃)₂), to enhance ionic conductivity, ifdesired.

Further examples of separators and separator materials suitable for useinclude those comprising a microporous xerogel layer, for example, amicroporous pseudo-boehmite layer, which may be provided either as afree standing film or by a direct coating application on one of theelectrodes, as described in U.S. Pat. No. 6,153,337, filed Dec. 19, 1997and, entitled “Separators for electrochemical cells,” and U.S. Pat. No.6,306,545 filed Dec. 17, 1998 and entitled “Separators forelectrochemical cells.” Solid electrolytes and gel electrolytes may alsofunction as a separator in addition to their electrolyte function.Examples of useful gel polymer electrolytes include, but are not limitedto, those comprising one or more polymers selected from the groupconsisting of polyethylene oxides, polypropylene oxides,polyacrylonitriles, polysiloxanes, polyimides, polyphosphazenes,polyethers, sulfonated polyimides, perfluorinated membranes (NAFIONresins), polydivinyl polyethylene glycols, polyethylene glycoldiacrylates, polyethylene glycol dimethacrylates, derivatives of theforegoing, copolymers of the foregoing, crosslinked and networkstructures of the foregoing, and blends of the foregoing, andoptionally, one or more plasticizers.

Other suitable materials that could be used to form all or part of theseparator include the separator materials described in U.S. PatentPublication No. 2010/0327811, filed Jul. 1, 2010 and published Dec. 30,2010, entitled “Electrode Protection in Both Aqueous and Non-AqueousElectromechanical Cells, Including Rechargeable Lithium Batteries,”which is incorporated herein by reference in its entirety for allpurposes.

Those of ordinary skill in the art, given the present disclosure, wouldbe capable of selecting appropriate materials for use as the separator.Relevant factors that might be considered when making such selectionsinclude the ionic conductivity of the separator material; the ability todeposit or otherwise form the separator material on or with othermaterials in the electrochemical cell; the flexibility of the separatormaterial; the porosity of the separator material (e.g., overallporosity, average pore size, pore size distribution, and/or tortuosity);the compatibility of the separator material with the fabrication processused to form the electrochemical cell; the compatibility of theseparator material with the electrolyte of the electrochemical cell;and/or the ability to adhere the separator material to the ion conductormaterial. In certain embodiments, the separator material can be selectedbased on its ability to survive ion conductor deposition processeswithout mechanically failing. For example, in embodiments in whichrelatively high temperatures or high pressures are used to form the ionconductor material (e.g., a ceramic ion conductor material), theseparator material can be selected or configured to withstand such hightemperatures and pressures.

Those of ordinary skill in the art can employ a simple screening test toselect an appropriate separator material from candidate materials. Onesimple screening test involves positioning a material as a separator inan electrochemical cell which, to function, requires passage of an ionicspecies across the material (e.g., through pores of the material) whilemaintaining electronic separation. If the material is substantiallyionically conductive in this test, then electrical current will begenerated upon discharging the electrochemical cell. Another simplescreening test involves the ability to increase the surface energy ofthe separator by various methods described herein. A screening test mayalso involve testing the adhesion between the separator and an ionconductor layer as described herein. Another screening test may involvetesting the ability of the separator to not swell in the presence of anelectrolyte to be used in an electrochemical cell. Other simple testscan be conducted by those of ordinary skill in the art.

The thickness of the separator may vary. The thickness of the separatormay vary over a range from, for example, 5 microns to 40 microns. Forinstance, the thickness of the separator may be between 10-20 microns,between 20-30 microns, or between 20-40 microns. The thickness of theseparator may be less than or equal to, e.g., 40 microns, less than orequal to 30 microns, less than or equal to 25 microns, less than orequal to 10 microns, or less than or equal to 9 microns. In someembodiments, the separator is at least 9 microns thick, at least 10microns thick, at least 20 microns thick, at least 25 microns thick, atleast 30 microns thick, or at least 40 microns thick. Other thicknessesare also possible. Combinations of the above-noted ranges are alsopossible.

As described herein, a separator may have a smooth surface. In someembodiments, the RMS surface roughness of a separator may be, forexample, less than 1 μm. In certain embodiments, the RMS surfaceroughness for such surfaces may be, for example, between 0.5 nm and 1 μm(e.g., between 0.5 nm and 10 nm, between 10 nm and 50 nm, between 10 nmand 100 nm, between 50 nm and 200 nm, between 10 nm and 500 nm). In someembodiments, the RMS surface roughness may be less than or equal to 0.9μm, less than or equal to 0.8 μm, less than or equal to 0.7 μm, lessthan or equal to 0.6 μm, less than or equal to 0.5 μm, less than orequal to 0.4 μm, less than or equal to 0.3 μm, less than or equal to 0.2μm, less than or equal to 0.1 μm, less than or equal to 75 nm, less thanor equal to 50 nm, less than or equal to 25 nm, less than or equal to 10nm, less than or equal to 5 nm, less than or equal to 2 nm, less than orequal to 1 nm. In some embodiments, the RMS surface roughness may begreater than 1 nm, greater than 5 nm, greater than 10 nm, greater than50 nm, greater than 100 nm, greater than 200 nm, greater than 500 nm, orgreater than 700 nm. Other values are also possible. Combinations of theabove-noted ranges are also possible (e.g., a RMS surface roughness ofless than or equal to 0.5 μm and greater than 10 nm.

As described herein, the separator may be porous. In some embodiments,the separator pore size may be, for example, less than 5 microns. Incertain embodiments, the separator pore size may be between 50 nm and 5microns, between 50 nm and 500 nm, between 100 nm and 300 nm, between300 nm and 1 micron, between 500 nm and 5 microns. In some embodiments,the pore size may be less than or equal to 5 microns, less than or equalto 1 micron, less than or equal to 500 nm, less than or equal to 300 nm,less than or equal to 100 nm, or less than or equal to 50 nm. In someembodiments, the pore size may be greater than 50 nm, greater than 100nm, greater than 300 nm, greater than 500 nm, or greater than 1 micron.Other values are also possible. Combinations of the above-noted rangesare also possible (e.g., a pore size of less than 300 nm and greaterthan 100 nm).

As described herein, the relative thickness of the ion conductor layerto the average pore diameter of the separator, which is positionedadjacent the ion conductor layer, may influence the degree of adhesivestrength of the two layers. For instance, the thickness of the ionconductor layer may be greater than the average pore diameter (orlargest pore diameter) of separator. In certain embodiments, the averagethickness of the ion conductor layer is at least 1.1 times, at least 1.2times, at least 1.5 times, at least 1.7 times, at least 2 times, atleast 2.5 times, at least 2.7 times, at least 2.8 times, at least 3.0times, at least 3.2 times, at least 3.5 times, at least 3.8 times, atleast 4.0 times, at least 5.0 times, at least 7.0 times, at least 10.0times, or at least 20.0 times the average pore size (or the largest porediameter) of the separator adjacent the ion conductor layer. In certainembodiments, the average thickness of the ion conductor layer may beless than or equal to 20.0 times, less than or equal to 10.0 times, lessthan or equal to 7.0 times, less than or equal to 5.0 times, less thanor equal to 4.0 times, less than or equal to 3.8 times, less than orequal to 3.5 times, less than or equal to 3.2 times, less than or equalto 3.0 times, less than or equal to 2.8 times, less than or equal to 2.5times, or less than or equal to 2 times the average pore size (or thelargest pore diameter) of the separator adjacent the ion conductorlayer. Other combinations of average pore diameter and ion conductorlayer thicknesses are also possible.

The ratio of thickness of the ion conductor layer to average porediameter of the separator may be, for example, at least 1:1 (e.g.,1.1:1), at least 2:1, at least 3:2, at least 3:1, at least 4:1, at least5:1, or at least 10:1. The ratio of thickness of the ion conductor layerto average pore diameter of the separator may be less than or equal to10:1, less than or equal to 5:1, less than or equal to 3:1, less than orequal to 2:1 (e.g., 1.1:1), or less than or equal to 1:1. Other ratiosare also possible. Combinations of the above-noted ranges are alsopossible.

As described herein, various methods may be used to form ionconductor/separator composite. The thickness of the composite may varyover a range from, for example, 5 microns to 40 microns. For instance,the thickness of the composite may be between 10-20 microns, between20-30 microns, or between 20-40 microns. The thickness of the compositemay be, for example, less than or equal to 40 microns, less than orequal to 30 microns, less than or equal to 25 microns, less than orequal to 10 microns, less than or equal to 9 microns, or less than orequal to 7 microns. In some embodiments, the composite is at least 5microns thick, at least 7 microns thick, at least 9 microns thick, atleast 10 microns thick, at least 20 microns thick, at least 25 micronsthick, at least 30 microns thick, or at least 40 microns thick. Otherthicknesses are also possible. Combinations of the above-noted rangesare also possible.

In some embodiments, the average ionic conductivity (e.g., lithium ionconductivity) of the composite is at least about 10⁻⁷ S/cm, at leastabout 10⁻⁶ S/cm, at least about 10⁻⁵ S/cm, at least about 10⁴ S/cm, atleast about 10⁻² S/cm, at least about 10⁻¹ S/cm, at least about 1 S/cm,at least about 10 S/cm. Conductivity may be measured at room temperature(e.g., 25 degrees Celsius).

A composite structure described herein including an ion conductor layerand a separator may be a free-standing structure that may be packagedalone (optionally with suitable components such as a substrate forhandling), together with an electroactive material to form a protectedelectrode, or assembled into an electrochemical cell.

In certain embodiments, an electrochemical cell comprises a firstelectrode comprising an electroactive material, a second electrode and acomposite positioned between the first and second electrodes. Thecomposite comprises a separator comprising pores having an average poresize and an inorganic ion conductor layer bonded to the separator. Theseparator may have a bulk electronic resistivity of at least 10⁴ Ohmmeters (e.g., at least 10¹⁰ Ohm meters, or at least 10¹⁵ Ohm meters,e.g., between 10¹⁰ Ohm meters to 10¹⁵ Ohm meters). The inorganic ionconductor layer has a lithium-ion conductivity of at least at least 10⁻⁶S/cm, and comprises a lithium oxysulfide having an oxide content between0.1-20 wt %.

The ion conductor layer comprising the lithium oxysulfide may be asingle layer in direct contact with each of the first electrode and theseparator. In other cases, the ion conductor layer is a part of amulti-layered structure comprising more than one ion conductor layers.Optionally, at least two layers of the multi-layered structure areformed of different materials. In other cases, at least two layers ofthe multi-layered structure are formed of the same material.

The lithium oxysulfide may have a formula of x(yLi₂S+zLi₂O)+MS₂ (where Mis Si, Ge, or Sn), where y+z=1, and where x may range from 0.5-3.Optionally, the ion conductor layer comprises a glass forming additiveranging from 0 wt % to 30 wt % of the inorganic ion conductor material.The ion conductor layer may also optionally comprise one or more lithiumsalts, such as LiI, LiBr, LiCl, Li₂CO₃, or Li₂SO₄, although other saltsdescribed herein are also possible. The one or more lithium salts may beadded to the inorganic ion conductor material at a range of, e.g., 0 to50 mol %.

The strength of adhesion between the separator and the inorganic ionconductor layer may be sufficiently strong to pass the tape testaccording to the standard ASTM D3359-02, in some instances. The strengthof adhesion between the separator and the inorganic ion conductor layermay be, in some cases, at least 350 N/m or at least 500 N/m. In somecases, the inorganic ion conductor layer is bonded to the separator bycovalent bonding. Covalent bonding may be achieved by suitable methodsdescribed herein, and one embodiment, involves plasma treatment of theseparator prior to addition or joining of the inorganic ion conductorlayer and the separator.

In some cases, a ratio of a thickness of the inorganic ion conductorlayer to the average pore size of the separator is at least 1.1:1 (e.g.,at least 2:1, at least 3:1, or at least 5:1).

The inorganic ion conductor layer may have a thickness of less than orequal to 2.0 microns (e.g., less than or equal to 1.5 microns, less thanor equal to 1.3 microns, less than or equal to 1 micron, less than orequal to 800 nm, less than or equal to 600 nm, or between 400 nm and 600nm).

In some instances, a separator having a thickness between 5 microns and40 microns is included. The separator may be a solid, polymericseparator. For instance, the separator may comprises or be formed of oneor more of poly(n-pentene-2), polypropylene, polytetrafluoroethylene, apolyamide (e.g., polyamide (Nylon), poly(ε-caprolactam) (Nylon 6),poly(hexamethylene adipamide) (Nylon 66)), a polyimide (e.g.,polynitrile, and poly(pyromellitimide-1,4-diphenyl ether) (Kapton®)(NOMEX®) (KEVLAR®)), polyether ether ketone (PEEK), and combinationsthereof. The separator may also comprise or be formed of other polymersor materials described herein.

In certain embodiments, a separator may comprise a mixture of apolymeric binder and a filler comprising a ceramic or a glassy/ceramicmaterial, such as a material described herein for an ion conductorlayer.

The separator may have an average pore size of less than or equal to 5microns, less than or equal to 1 micron, less than or equal to 0.5microns, between 0.05-5 microns, or between 0.1-0.3 microns.

The composite may have an air permeation time of at least 20,000Gurley-s, at least 40,000 Gurley-s, at least 60,000 Gurley-s, at least80,000 Gurley-s, at least 100,000 Gurley-s, or at least 120,000 Gurley-saccording to Gurley test TAPPI Standard T 536 om-12. The composite mayhave an air permeation time of less than or equal to 300,000 Gurley-saccording to Gurley test TAPPI Standard T 536 om-12.

The composite may be formed by, for example, depositing the ionconductor layer onto the separator by a vacuum deposition process suchas electron beam evaporation or by a sputtering process.

Although the composites described herein may be used in variouselectrochemical cells, in one set of embodiments, the composite isincluded in a lithium cell, such as a lithium-sulfur cell. Accordingly,a first electrode may comprise lithium, such as lithium metal and/or alithium alloy, as a first electroactive material, and a second electrodecomprises sulfur as a second electroactive material.

In one set of embodiments, the electrochemical cell is a lithium-sulfurcell comprising a first electrode comprising lithium, a second electrodecomprising sulfur, a separator arranged between said first electrode andsaid second electrode, and a solid ion conductor contacting and/orbonded to the separator, wherein said solid ion conductor comprises alithium-ion conducting oxysulfide.

In embodiments in which a polymer layer is positioned on a substrate(e.g., an ion conductor layer), e.g., as part of a multi-layerprotective structure, it should be appreciated that the polymer layermay be cured or otherwise prepared directly onto the substrate, or thepolymer may be added separately to the substrate.

The polymer layer can be a solid (e.g., as opposed to a gel). Thepolymer layer can be configured to be electronically non-conductive, incertain embodiments, and may be formed of a material with a bulkelectronic resistivity of at least about 10⁴, at least about 10⁵, atleast about 10¹⁰, at least about 10¹⁵, or at least about 10²⁰Ohm-meters.

In some embodiments, the polymer can be ionically conductive. In someembodiments, the average ionic conductivity of the polymer is at leastabout 10⁻⁷ S/cm, at least about 10⁻⁶ S/cm, at least about 10⁻⁵ S/cm, atleast about 10⁻⁴ S/cm, at least about 10⁻² S/cm, at least about 10⁻¹S/cm. In certain embodiments, the average ionic conductivity of thepolymer may be less than or equal to about 1 S/cm, less than or equal toabout 10⁻¹ S/cm, less than or equal to about 10⁻² S/cm, less than orequal to about 10⁻³ S/cm, less than or equal to about 10⁻⁴ S/cm, lessthan or equal to about 10⁻⁵ S/cm, less than or equal to about 10⁻⁶ S/cm,less than or equal to about 10⁻⁷ S/cm, or less than or equal to about10⁻⁸ S/cm. Combinations of the above-referenced ranges are also possible(e.g., an average ionic conductivity of at least about 10⁻⁸ S/cm andless than or equal to about 10⁻¹ S/cm). Conductivity may be measured atroom temperature (e.g., 25 degrees Celsius).

A polymer layer described herein can be made of a variety of materials.Examples of materials that may be suitable for use in the polymer layerinclude, but are not limited to, polyamines (e.g., poly(ethylene imine)and polypropylene imine (PPI)); polyamides (e.g., polyamide (Nylon),poly(e-caprolactam) (Nylon 6), poly(hexamethylene adipamide) (Nylon66)), polyimides (e.g., polyimide, polynitrile, andpoly(pyromellitimide-1,4-diphenyl ether) (Kapton)); vinyl polymers(e.g., polyacrylamide, poly(2-vinyl pyridine), poly(N-vinylpyrrolidone),poly(methylcyanoacrylate), poly(ethylcyanoacrylate),poly(butylcyanoacrylate), poly(isobutylcyanoacrylate), poly(vinylacetate), poly (vinyl alcohol), poly(vinyl chloride), poly(vinylfluoride), poly(2-vinyl pyridine), vinyl polymer, polychlorotrifluoroethylene, and poly(isohexylcynaoacrylate)); polyacetals; polyolefins(e.g., poly(butene-1), poly(n-pentene-2), polypropylene,polytetrafluoroethylene); polyesters (e.g., polycarbonate, polybutyleneterephthalate, polyhydroxybutyrate); polyethers (poly(ethylene oxide)(PEO), poly(propylene oxide) (PPO), poly(tetramethylene oxide) (PTMO));vinylidene polymers (e.g., polyisobutylene, poly(methyl styrene),poly(methylmethacrylate) (PMMA), poly(vinylidene chloride), andpoly(vinylidene fluoride)); polyaramides (e.g., poly(imino-1,3-phenyleneiminoisophthaloyl) and poly(imino-1,4-phenylene iminoterephthaloyl));polyheteroaromatic compounds (e.g., polybenzimidazole (PBI),polybenzobisoxazole (PBO) and polybenzobisthiazole (PBT));polyheterocyclic compounds (e.g., polypyrrole); polyurethanes; phenolicpolymers (e.g., phenol-formaldehyde); polyalkynes (e.g., polyacetylene);polydienes (e.g., 1,2-polybutadiene, cis or trans-1,4-polybutadiene);polysiloxanes (e.g., poly(dimethylsiloxane) (PDMS),poly(diethylsiloxane) (PDES), polydiphenylsiloxane (PDPS), andpolymethylphenylsiloxane (PMPS)); and inorganic polymers (e.g.,polyphosphazene, polyphosphonate, polysilanes, polysilazanes). In someembodiments, the polymer may be selected from the group consisting ofpolyvinyl alcohol, polyisobutylene, epoxy, polyethylene, polypropylene,polytetrafluoroethylene, and combinations thereof. The mechanical andelectronic properties (e.g., conductivity, resistivity) of thesepolymers are known. Accordingly, those of ordinary skill in the art canchoose suitable polymers based on their mechanical and/or electronicproperties (e.g., ionic and/or electronic conductivity), and/or canmodify such polymers to be ionically conducting (e.g., conductivetowards single ions) based on knowledge in the art, in combination withthe description herein. For example, the polymer materials listed abovemay further comprise salts, for example, lithium salts (e.g., LiSCN,LiBr, LiI, LiClO₄, LiAsF₆, LiSO₃CF₃, LiSO₃CH₃, LiBF₄, LiB(Ph)₄, LiPF₆,LiC(SO₂CF₃)₃, and LiN(SO₂CF₃)₂), to enhance ionic conductivity.

Those of ordinary skill in the art, given the present disclosure, wouldbe capable of selecting appropriate materials for use as a polymerlayer. Relevant factors that might be considered when making suchselections include the ionic conductivity of the polymer material; theability to deposit or otherwise form the polymer material on or withother materials in the electrochemical cell; the flexibility of thepolymer material; the porosity of the polymer material (e.g., overallporosity, pore size distribution, and/or tortuosity); the compatibilityof the polymer material with the fabrication process used to form theelectrochemical cell; the compatibility of the polymer material with theelectrolyte of the electrochemical cell; and/or the ability to adherethe polymer material to the ion conductor material.

The thickness of the polymer layer may vary. The thickness of thepolymer layer may be less than or equal to, e.g., 40 microns, less thanor equal to 30 microns, less than or equal to 25 microns, less than orequal to 10 microns, less than or equal to 5 microns, less than or equalto 3 microns, less than or equal to 2 microns, less than or equal to 1micron, less than or equal to 0.5 microns, less than or equal to 0.1microns, less than or equal to 0.05 microns. In some embodiments, thepolymer layer is at least 0.01 microns thick, at least 0.05 micronsthick, at least 0.1 microns thick, at least 0.5 microns thick, at least1 micron thick, at least 2 microns thick, at least 5 microns thick, atleast 10 microns thick, at least 20 microns thick, at least 25 micronsthick, at least 30 microns thick, or at least 40 microns thick. Otherthicknesses are also possible. Combinations of the above-noted rangesare also possible.

In some embodiments, an electrode, such as a first electrode (e.g.,electrode 102 in FIGS. 1A and 1B) comprises an electroactive materialcomprising lithium. Suitable electroactive materials comprising lithiuminclude, but are not limited to, lithium metal (such as lithium foiland/or lithium deposited onto a conductive substrate) and lithium metalalloys (e.g., lithium-aluminum alloys and lithium-tin alloys). In someembodiments, the electroactive lithium-containing material of anelectrode comprises greater than 50 wt % lithium. In some cases, theelectroactive lithium-containing material of an electrode comprisesgreater than 75 wt % lithium. In still other embodiments, theelectroactive lithium-containing material of an electrode comprisesgreater than 90 wt % lithium. Other examples of electroactive materialsthat can be used (e.g., in the first electrode, which can be a negativeelectrode) include, but are not limited to, other alkali metals (e.g.,sodium, potassium, rubidium, caesium, francium), alkaline earth metals(e.g., beryllium, magnesium, calcium, strontium, barium, radium), andthe like. In some embodiments, the first electrode is an electrode for alithium ion electrochemical cell. In some cases, the first electrode isan anode or negative electrode.

The second electrode (e.g., electrode 102 in FIGS. 1A and 1B) cancomprise a variety of suitable electroactive materials. In some cases,the second electrode is a cathode or positive electrode.

In some embodiments, the electroactive material within an electrode(e.g., within a positive electrode) can comprise metal oxides, such asLiCoO₂, Ni_((1-x))O₂, LiCo_(x)Ni_(y)Mn_((1-x-y)) (e.g.,LiNi_(1/3)Mn_(1/3)Co_(1/3)O₂), LiMn₂O₄, and combinations thereof. Insome embodiments, the electrode active material within an electrode(e.g., within a positive electrode) can comprise lithium transitionmetal phosphates (e.g., LiFePO₄), which can, in certain embodiments, besubstituted with borates and/or silicates.

In certain embodiments, the electroactive material within an electrode(e.g., within a positive electrode) can comprise electroactivetransition metal chalcogenides, electroactive conductive polymers,and/or electroactive sulfur-containing materials, and combinationsthereof. As used herein, the term “chalcogenides” pertains to compoundsthat contain one or more of the elements of oxygen, sulfur, andselenium. Examples of suitable transition metal chalcogenides include,but are not limited to, the electroactive oxides, sulfides, andselenides of transition metals selected from the group consisting of Mn,V, Cr, Ti, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf Ta, W, Re,Os, and Ir. In one embodiment, the transition metal chalcogenide isselected from the group consisting of the electroactive oxides ofnickel, manganese, cobalt, and vanadium, and the electroactive sulfidesof iron. In one embodiment, an electrode (e.g., a positive electrode)can comprise an electroactive conductive polymer. Examples of suitableelectroactive conductive polymers include, but are not limited to,electroactive and electronically conductive polymers selected from thegroup consisting of polypyrroles, polyanilines, polyphenylenes,polythiophenes, and polyacetylenes. In certain embodiments, it may bedesirable to use polypyrroles, polyanilines, and/or polyacetylenes asconductive polymers.

In certain embodiments, the electrode active material within anelectrode (e.g., within a positive electrode) can comprise sulfur. Insome embodiments, the electroactive material within an electrode cancomprise electroactive sulfur-containing materials. “Electroactivesulfur-containing materials,” as used herein, refers to electrode activematerials which comprise the element sulfur in any form, wherein theelectrochemical activity involves the oxidation or reduction of sulfuratoms or moieties. As an example, the electroactive sulfur-containingmaterial may comprise elemental sulfur (e.g., S₈). In some embodiments,the electroactive sulfur-containing material comprises a mixture ofelemental sulfur and a sulfur-containing polymer. Thus, suitableelectroactive sulfur-containing materials may include, but are notlimited to, elemental sulfur, sulfides or polysulfides (e.g., of alkalimetals) which may be organic or inorganic, and organic materialscomprising sulfur atoms and carbon atoms, which may or may not bepolymeric. Suitable organic materials include, but are not limited to,those further comprising heteroatoms, conductive polymer segments,composites, and conductive polymers. In some embodiments, anelectroactive sulfur-containing material within an electrode (e.g., apositive electrode) comprises at least about 40 wt % sulfur. In somecases, the electroactive sulfur-containing material comprises at leastabout 50 wt %, at least about 75 wt %, or at least about 90 wt % sulfur.

Examples of sulfur-containing polymers include those described in: U.S.Pat. Nos. 5,601,947 and 5,690,702 to Skotheim et al.; U.S. Pat. Nos.5,529,860 and 6,117,590 to Skotheim et al.; U.S. Pat. No. 6,201,100issued Mar. 13, 2001, to Gorkovenko et al., and PCT Publication No. WO99/33130. Other suitable electroactive sulfur-containing materialscomprising polysulfide linkages are described in U.S. Pat. No. 5,441,831to Skotheim et al.; U.S. Pat. No. 4,664,991 to Perichaud et al., and inU.S. Pat. Nos. 5,723,230, 5,783,330, 5,792,575 and 5,882,819 to Naoi etal. Still further examples of electroactive sulfur-containing materialsinclude those comprising disulfide groups as described, for example in,U.S. Pat. No. 4,739,018 to Armand et al.; U.S. Pat. Nos. 4,833,048 and4,917,974, both to De Jonghe et al.; U.S. Pat. Nos. 5,162,175 and5,516,598, both to Visco et al.; and U.S. Pat. No. 5,324,599 to Oyama etal.

While sulfur is described predominately as an electroactive species inthe second electrode (which can be, for example, a porous positiveelectrode), it is to be understood that wherever sulfur is described asa component of an electroactive material within an electrode herein, anysuitable electroactive species may be used. For example, in certainembodiments, the electroactive species within the second electrode(e.g., a porous positive electrode) can comprise a hydrogen-absorbingalloy, such as those commonly used in nickel metal hydride batteries.One of ordinary skill in the art, given the present disclosure, would becapable of extending the ideas described herein to electrochemical cellscontaining electrodes employing other active materials.

The embodiments described herein may be used in association with anytype of electrochemical cell. In certain embodiments, theelectrochemical cell is a primary (non-rechargeable) battery. In otherembodiments, the electrochemical cell may be a secondary (rechargeable)battery. Certain embodiments relate to lithium rechargeable batteries.In certain embodiments, the electrochemical cell comprises alithium-sulfur rechargeable battery. However, wherever lithium batteriesare described herein, it is to be understood that any analogous alkalimetal battery can be used. Additionally, although embodiments of theinvention are particularly useful for protection of a lithium anode, theembodiments described herein may be applicable to other applications inwhich electrode protection is desired.

Any suitable electrolyte may be used in the electrochemical cellsdescribed herein. Generally, the choice of electrolyte will depend uponthe chemistry of the electrochemical cell, and, in particular, thespecies of ion that is to be transported between electrodes in theelectrochemical cell. Suitable electrolytes can comprise, in someembodiments, one or more ionic electrolyte salts to provide ionicconductivity and one or more liquid electrolyte solvents, gel polymermaterials, or other polymer materials. Examples of useful non-aqueousliquid electrolyte solvents include, but are not limited to, non-aqueousorganic solvents, such as, for example, N-methyl acetamide,acetonitrile, acetals, ketals, esters, carbonates, sulfones, sulfites,sulfolanes, aliphatic ethers, cyclic ethers, glymes, polyethers,phosphate esters, siloxanes, dioxolanes (e.g., 1,3-dioxolane),N-alkylpyrrolidones, bis(trifluoromethanesulfonyl)imide, substitutedforms of the foregoing, and blends thereof. Fluorinated derivatives ofthe foregoing are also useful as liquid electrolyte solvents. In somecases, aqueous solvents can be used as electrolytes for lithium cells.Aqueous solvents can include water, which can contain other componentssuch as ionic salts. In some embodiments, the electrolyte can includespecies such as lithium hydroxide, or other species rendering theelectrolyte basic, so as to reduce the concentration of hydrogen ions inthe electrolyte.

The electrolyte can comprise one or more ionic electrolyte salts toprovide ionic conductivity. In some embodiments, one or more lithiumsalts (e.g., LiSCN, LiBr, LiI, LiClO₄, LiAsF₆, LiSO₃CF₃, LiSO₃CH₃,LiBF₄, LiB(Ph)₄, LiPF₆, LiC(SO₂CF₃)₃, and LiN(SO₂CF₃)₂) can be included.Other electrolyte salts that may be useful include lithium polysulfides(Li₂S_(x)), and lithium salts of organic ionic polysulfides(LiS_(x)R)_(n), where x is an integer from 1 to 20, n is an integer from1 to 3, and R is an organic group, and those disclosed in U.S. Pat. No.5,538,812 to Lee et al. A range of concentrations of the ionic lithiumsalts in the solvent may be used such as from about 0.2 m to about 2.0 m(m is moles/kg of solvent). In some embodiments, a concentration in therange between about 0.5 m to about 1.5 m is used. The addition of ioniclithium salts to the solvent is optional in that upon discharge of Li/Scells the lithium sulfides or polysulfides formed typically provideionic conductivity to the electrolyte, which may make the addition ofionic lithium salts unnecessary.

It should be understood that the electrochemical cells and componentsshown in is the figures are exemplary, and the orientation of thecomponents can be varied. Additionally, non-planar arrangements,arrangements with proportions of materials different than those shown,and other alternative arrangements are useful in connection with certainembodiments of the present invention. A typical electrochemical cellcould also include, for example, a containment structure, currentcollectors, external circuitry, and the like. Those of ordinary skill inthe art are well aware of the many arrangements that can be utilizedwith the general schematic arrangement as shown in the figures anddescribed herein.

As used herein, when a layer is referred to as being “on”, “on top of”,or “adjacent” another layer, it can be directly on, on top of, oradjacent the layer, or an intervening layer may also be present. A layerthat is “directly on”, “directly adjacent” or “in contact with” anotherlayer means that no intervening layer is present. Likewise, a layer thatis positioned “between” two layers may be directly between the twolayers such that no intervening layer is present, or an interveninglayer may be present.

The following example is intended to illustrate certain embodiments ofthe present invention, but does not exemplify the full scope of theinvention.

EXAMPLES Example 1A

This example describes a method for generating an ion conductor layer ona free-standing separator (e.g., an ion conductor-separator composite),with improved adhesive strength between the layers.

A commercial separator, Celgard 2400, having a pore diameter between 100nm to 200 nm, was used as a substrate. The separator was pre-treatedwith plasma using an Anode Layer Ion Source in a chamber at a pressureof 10⁻³ Torr, a power of 50 W, in the presence of argon gas. Thetreatment continued for 7 minutes. Before plasma treatment, the surfaceenergy of the separator was 32 dynes. The separator surface energy afterplasma treatment was greater than 70 dynes, as measured by a dyne penset.

Next, a layer of lithium oxysulfide, an ion conductor, was depositedonto the separator to form an ion conductor layer by e-beam evaporation.The major components of the lithium oxysulfide layer were lithium,silicon, sulfur and oxygen, with the following ratios: 1.5:1 for Si:O,4.5:1 for S:O, and 3.1:1 for S:Si. In three experiments, the thicknessof the ion conductor layer ranged from about 600-800 nm, as shown inFIGS. 4A-4C. The ratio of thickness of the ion conductor layer to porediameter of the separator in these experiments ranged from about 3:1 to8:1.

FIGS. 4A, 4B, and 4C are scanning electron microscopy (SEM) imagesshowing the ion conductor (lithium oxysulfide) coating on the commercialseparator. FIG. 4A is an SEM of the lithium oxysulfide coating on a25-micron-thick separator. The thickness of the lithium oxysulfide layerwas 610 nm. FIG. 4B is an SEM of a lithium oxysulfide layer on a 25micron separator. The thickness of the lithium oxysulfide layer was 661nm. FIG. 4C is an SEM cross-sectional image of an 800 nm thick lithiumoxysulfide coating on the separator material. These images also showthat the lithium oxysulfide material did not penetrate into theseparator's pores.

A tape test was performed according to standard ASTM-D3359-02 todetermine adhesiveness between the ion conductor layer and theseparator. The test demonstrated that the ion conductor was well bondedto the separator and did not delaminate from the separator.

This example shows that pre-treatment of the surface of the separatorwith plasma prior to deposition of an ion conductor (lithium oxysulfide)layer enhanced adhesion of the ion conductor layer to the separator,compared to the absence of a pre-treatment step (Comparative Example 1).

Example 1B

An ion conductor-separator composite similar to that described inExample 1A was formed except the lithium oxysulfide ion conductor layerhad a thickness of 1 micron. The surface of the separator was treated toplasma as described in Example 1A prior to deposition of the lithiumoxysulfide layer.

The final composite demonstrated 17 times reduced air permeation ratescompared with an untreated separator (i.e., a separator that was nottreated to plasma prior to deposition of the lithium oxysulfide layer,Comparative Example 1), as determined by a Gurley test performed with apressure differential of 3 kPa (TAPPI Standard T 536 om-12). The finalcomposite had an air permeation time of over 168 minutes, compared toabout 9.7 minutes for the composite including the untreated separator(Comparative Example 1).

This example shows that pre-treatment of the surface of the separatorwith plasma prior to deposition of an ion conductor (lithium oxysulfide)layer enhanced air permeation time of the composite, compared to acomposite that included an untreated separator (Comparative Example 1).

Comparative Example 1

The following is a comparative example describing an ion conductor layerthat was poorly bonded to a separator.

The method described in Example 1 was used to form an ionconductor-separator composite, except here the separator was not treatedwith plasma prior to deposition of the ion conductor layer.

The ion conductor-separator composite did not pass the tape test,demonstrating delamination of the ion conductor layer from theseparator.

At a ceramic thickness of 1 micron, the air permeation time was below9.7 minutes as determined by a Gurley Test (TAPPI Standard T 536 om-12).

Example 2

This example shows the formation and performance of the ionconductor-separator composite of Example 1 in a lithium-sulfurelectrochemical cell.

The ion conductor (lithium oxysulfide)-coated separator of Example 1 wasvacuum coated with metallic lithium (25 microns of lithium deposited ontop of the lithium oxysulfide layer). The lithium anode was protectedwith the lithium oxysulfide-coated separator and was assembled into alithium-sulfur battery cell.

The cathode contained 55% weight percent sulfur, 40% weight percent ofcarbon black and 5% weight percent of polyvinyl alcohol binder. Thesulfur surface loading was approximately 2 mg/cm².

The active electrode covered a total surface area of 16.57 cm². Thelithium-sulfur battery cells were filled with an electrolyte containing16% weight percent of lithium bis(Trifluoromethanesulfonyl)imide, 42%weight percent of dimethoxyethane, and 42% weight percent of1,3-dioxolane solvents.

The lithium-sulfur battery cells were discharged at 3 mA to 1.7 V andwere charged at 3 mA. Charge was terminated when the lithium-sulfurbattery cell reached 2.5 V or when charge time exceeded 15 hours if thecells were not able reaching 2.5 V.

The lithium-sulfur battery cells were cycled over 30 times and showedthe ability to reach 2.5 V at every cycle, demonstrating that thelithium oxysulfide layer performed well as a barrier, protecting lithiumfrom the polysulfide shuttle. Multiple cells autopsied after 10 chargecycles showed no defects in the lithium oxysulfide layer and showed noevidence of lithium metal deposition on top of the lithium oxysulfidelayer. All lithium was deposited under the lithium oxysulfide layer.Autopsies also showed that the ceramic and separator materials were wellbonded after cycling.

Comparative Example 2

This example shows the formation and performance of the ionconductor-separator composite of Comparative Example 1 in alithium-sulfur electrochemical cell.

Anodes with vacuum deposited lithium on the top of the ionconductor-separator composite of Comparative Example 1 were assembledinto lithium-sulfur battery cells and tested similarly as described inExample 2.

These cells were unable to be charged to 2.5 V over 30 cycles. Instead,charge time was at least 15 hours and charge voltage leveled at2.37-2.41 V. These results demonstrate that the lithium was notprotected from the polysulfide shuttle during cycling. Autopsy showedthat the lithium oxysulfide layer had defects and a substantial portionof lithium (˜20-30% of the surface area) was deposited on the top ofthis layer.

Example 3

This example demonstrates the ability of ion conductor-separatorcomposites (fabricated similarly to the method described in Example 1)to act as a barrier to fluids, as demonstrated by air permeation testing(Gurley test). Each of the samples included a 25 micron thick separatorwith pore diameters ranging between 0.1 micron to 0.5 microns, and acoating of lithium oxysulfide on top of the separator. Samples 1, 2, 3,and 6 included separators that were plasma treated before the additionof the lithium oxysulfide. Samples 4, 5, and 7 included separators thatwere untreated before the addition of the lithium oxysulfide layer.

FIG. 5 is a graph showing air permeation time versus ion conductor layerthickness for composites including plasma treated and untreatedseparators. The figure highlights the improvement in air permeationtimes with plasma treatment of the separator before applying the lithiumoxysulfide coating, i.e., samples 1, 2, 3, and 6, compared to compositesthat included separators that were untreated before the addition of thelithium oxysulfide layer (samples 4, 5, and 7).

This example demonstrates that air permeation time generally increaseswhen the surface of the separator of the is subjected to plasmatreatment prior to deposition of the oxysulfide layer, which promotessufficient bonding between the oxysulfide layer and the separator. Theabsence of plasma treatment resulted in delamination of the oxysulfidelayer, and therefore leads to poorer barrier properties. This examplealso shows that the highest air permeation time (and, therefore,enhanced barrier properties) was achieved with a lithium oxysulfidelayer having a thickness of 0.5 microns (sample 1). This data suggeststhat thinner lithium oxysulfide layers generally lead to improvedbarrier properties compared to composites having thicker lithiumoxysulfide layers, with the combination of a thin lithium oxysulfidelayer and a plasma treated separator showing the highest air permeationtime (and, therefore, enhanced barrier properties).

While several embodiments of the present invention have been describedand illustrated herein, those of ordinary skill in the art will readilyenvision a variety of other means and/or structures for performing thefunctions and/or obtaining the results and/or one or more of theadvantages described herein, and each of such variations and/ormodifications is deemed to be within the scope of the present invention.More generally, those skilled in the art will readily appreciate thatall parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the teachings of thepresent invention is/are used. Those skilled in the art will recognize,or be able to ascertain using no more than routine experimentation, manyequivalents to the specific embodiments of the invention describedherein. It is, therefore, to be understood that the foregoingembodiments are presented by way of example only and that, within thescope of the appended claims and equivalents thereto, the invention maybe practiced otherwise than as specifically described and claimed. Thepresent invention is directed to each individual feature, system,article, material, and/or method described herein. In addition, anycombination of two or more such features, systems, articles, materials,and/or methods, if such features, systems, articles, materials, and/ormethods are not mutually inconsistent, is included within the scope ofthe present invention.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Other elements may optionallybe present other than the elements specifically identified by the“and/or” clause, whether related or unrelated to those elementsspecifically identified unless clearly indicated to the contrary. Thus,as a non-limiting example, a reference to “A and/or B,” when used inconjunction with open-ended language such as “comprising” can refer, inone embodiment, to A without B (optionally including elements other thanB); in another embodiment, to B without A (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.

As used herein in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the claims, “consisting of,” will refer to the inclusion of exactlyone element of a number or list of elements. In general, the term “or”as used herein shall only be interpreted as indicating exclusivealternatives (i.e. “one or the other but not both”) when preceded byterms of exclusivity, such as “either,” “one of,” “only one of,” or“exactly one of.” “Consisting essentially of,” when used in the claims,shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc.

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” and the like are to be understoodto be open-ended, i.e., to mean including but not limited to. Only thetransitional phrases “consisting of” and “consisting essentially of”shall be closed or semi-closed transitional phrases, respectively, asset forth in the United States Patent Office Manual of Patent ExaminingProcedures, Section 2111.03.

What is claimed is:
 1. A process of making an electrochemical cell,comprising the following steps: providing a separator comprising pores,wherein the separator has a bulk electronic resistivity of at leastabout 10⁴ Ohm-meters; bonding a solid ion conductor layer to theseparator to form a composite, wherein the separator and the solid ionconductor layer have a strength of adhesion that passes a tape testaccording to standard ASTM D3359-02, wherein the solid ion conductorlayer comprises a lithium oxysulfide, and wherein the solid ionconductor layer is substantially formed of a non-polymeric material; andassembling the electrochemical cell.
 2. A process according to claim 1,wherein bonding the solid ion conductor layer to the separator isachieved by depositing an ion conductor material onto the surface of theseparator.
 3. A process according to claim 1, wherein an intermediateproduct obtained by bonding the solid ion conductor layer to theseparator is a composite which is a free-standing structure.
 4. Aprocess according to claim 1, comprising positioning the compositebetween a first electrode and a second electrode.
 5. A process accordingto claim 1, wherein the solid ion conductor layer comprises the lithiumoxysulfide having an atomic ratio of oxygen atoms to sulfur atoms (O:S)in the range of from 0.01:1 to 0.25:1.
 6. A process according to claim1, wherein the solid ion conductor layer comprising the lithiumoxysulfide is a part of a multi-layered structure comprising more thanone ion conductor layers.
 7. A process according to claim 6, wherein atleast two layers of the multi-layered structure are formed of differentmaterials.
 8. A process according to claim 1, comprising positioning thesolid ion conductor layer comprising the lithium oxysulfide to be indirect contact with each of a first electrode and the separator.
 9. Aprocess according to claim 1, wherein the separator has a bulkelectronic resistivity between 10¹⁰ Ohm-meters and 10¹⁵ Ohm-meters. 10.A process according to claim 1, wherein the separator is a solid,polymeric separator.
 11. A process according to claim 1, wherein theseparator is a solid comprising a mixture of a polymeric binder and afiller comprising a ceramic or a glassy/ceramic material.
 12. A processaccording to claim 1, wherein the separator comprises one or more ofpoly(n-pentene-2), polypropylene, polytetrafluoroethylene, a polyamide(e.g., polyamide (Nylon), poly(ε-caprolactam) (Nylon 6),poly(hexamethylene adipamide) (Nylon 66)), a polyimide (e.g.,polynitrile, and poly(pyromellitimide-1,4-diphenyl ether) (Kapton®)(NOMEX®) (KEVLAR®)), polyether ether ketone (PEEK), and combinationsthereof.
 13. A process according to claim 1, wherein the lithiumoxysulfide has a formula of x(yLi₂S+zLi₂O)+MS₂ (where M is Si, Ge, orSn), where y+z=1, and where x may range from 0.5-3.
 14. A processaccording to claim 1, wherein the solid ion conductor layer comprises aglass-forming additive ranging from 0 wt % to 30 wt % of a solid ionconductor material.
 15. A process according to claim 1, wherein theseparator has an average pore size of less than or equal to 0.5 microns.16. A process according to claim 1, wherein the solid ion conductorlayer has a thickness of less than or equal to 800 nm.
 17. A processaccording to claim 1, wherein the composite has a lithium ionconductivity of at least 10⁻⁵ S/cm at 25 degrees Celsius.
 18. A processaccording to claim 1, wherein a ratio of a thickness of the solid ionconductor layer to an average pore size of the separator is at least1.1:1 and less than or equal to 20:1.
 19. A process according to claim1, wherein the strength of adhesion between the separator and the solidion conductor layer is at least 50 N/m and less than or equal to 2000N/m.
 20. A process according to claim 1, wherein the solid ion conductorlayer serves as a solvent barrier in the electrochemical cell.